According to Rufus, having a conversation with the Space Troll required patience or a sense of humor. The fact that novice hams were screwing around on the radio, which would have driven Rufus into a spasm of righteous fury a few years ago, now just seemed like a sign of the times. Of course people were getting interested in amateur radio; the Internet was expected to go down as soon as the Hard Rain started. And of course many of them were novices.
When they finally did begin an intelligible conversation, Rufus would send QTH, which meant “where are you?” and would get back QET. This was an unofficial Q code, a sort of corny joke meaning “not on planet Earth.”
And that was why Rufus called this guy the Space Troll. Because, among other oddities, he didn’t have a call sign, or at least didn’t use one. The signal she was hearing now was QRA QET, repeated every few seconds; it meant, basically, “Hello, this is E.T., is anyone listening?”
Dinah generally kept the transmit side of her rig turned off when not in use. She turned it on now, but kept her hand well clear of the brass telegraph key. Lurking and listening were harmless, but as soon as she touched that thing, the Space Troll would hear an answering beep, and then she might never be rid of him. More likely, though, was that the Space Troll would give up after a while. Then she could transmit to Rufus, who’d be coming up over the horizon in a few minutes, and let him know that she too had heard from the mysterious “extraterrestrial.” It would be good for a laugh, and a few minutes’ distraction. Her father sounded like he could use some of both.
It had long since become obvious that he and a number of his mining industry friends had mounted a serious operation to prepare for an extended stay beneath the surface of the Earth. They were hardly the only ones to think that way; people were digging holes in the ground all over the world. Most of them would be dead within hours or days of the beginning of the Hard Rain. Constructing an underground complex that could sustain itself for thousands of years was an operation of which few, if any, organizations were capable. Most of those were governmental or military. But if any private group could do it, it was Rufus and his network. The sorts of questions he had been asking her for the last two years left nothing to the imagination. To the extent that the experts on Izzy knew anything about long-term sustainability of artificial ecosystems, Rufus now knew it too.
Distracted by thinking about Rufus and his mine, Dinah became aware that the Space Troll’s transmission had changed. Instead of the familiar QRA QET, it now began with QSO, which in this context meant “can you communicate with . . . ?” This was followed by an unfamiliar call sign, which she didn’t recognize as such because it was so long: a string of digits and letters that didn’t follow any of the standard conventions for radio call signs.
The third time this transmission was repeated, she wrote it down: twelve characters in all, a basically random assortment of digits and letters. But she did notice that all the letters were in the range A through F. Which was a strong hint that this was a number expressed in hexadecimal notation: a system typically used by computer programmers.
The fact that it had twelve digits was also a clue. The network chips used by almost all computer systems had unique addresses in that format: twelve hexadecimal digits.
And here was where Dinah got a weird feeling on the back of her neck, because the first few digits in that string looked familiar to her. Network interface chips were produced in large batches, with unique addresses assigned to each chip in sequence. So, just as all Fords rolling off the assembly line in a given week might have serial numbers beginning with the same few characters, all the network chips in a given batch would start with the same few hex digits. Some of Dinah’s chips were cheap off-the-shelf hardware made for terrestrial use, but she also had some rad-hard ones, which she hoarded in a shielded box in a drawer beneath her workstation.
She opened that drawer, pulled out that box, and took out a little green PC board, about the size of a stick of gum, with an assortment of chips mounted to it. Printed in white capital letters directly on the board was its MAC address. And its first half-dozen digits matched those in the transmission coming from the Space Troll.
She reached for the key and coded in QSO, meaning, in this context, “yes, I can communicate with . . .” and then keyed in the full MAC address of the little board in her hand—different from the one in the original transmission. It was a way of saying, “no, I can’t communicate with the one you mentioned, but I can communicate with this other one.”
QSB, came the answer back. “Your signals are fading.” Then QTX 46, which she guessed meant something like “Will you be available on this frequency forty-six minutes from now?” As anyone on Izzy would understand, this meant “I will call you back when you have orbited around to the other side of the planet.”
QTX 46, she answered back. “Yes.”
They were passing over the terminator, currently dividing the Pacific into a day side and a night side.
WHO THE HELL ARE YOU TALKING TO?
This was a transmission from Rufus, loud and clear. She looked out the window to see the West Coast of North America creeping over the horizon toward them, identifiable as a pattern of lights delineating the conurbations of the Fraser Delta, Puget Sound, the Columbia River, San Francisco Bay. Which meant that Alaska had line of sight to Izzy.
“Knock knock!” came the voice of Dubois Harris through the curtain. He’d been waiting there a long time.
“Come in,” Dinah said, and keyed back a brief transmission to Rufus making a joke about the Space Troll and telling him she would be in touch later. She checked the world clock app on her computer screen. It was shortly before dot 7, therefore 7:00 A.M. in London, therefore ten in the evening for Rufus in Alaska.
A somewhat distracted and scattered conversation followed, Dinah trying to maintain a train of thought with Doob while fielding sporadic, peremptory interruptions from Rufus. “Something kinda weird just happened on the radio,” she said. “Do you want a drink? It’s evening for you, right?”
“I pretty much always want one,” Doob said. “Let’s not worry about it. What’s up?”
Dinah related the story. Doob looked distracted at first, perhaps because of all the ham radio jargon, but focused when she showed him the MAC addresses.
“The simplest explanation,” he pointed out, “is that it’s a troll, just messing with you.”
“But how would a troll know those MAC addresses? We don’t give those out—we don’t want our robots getting hacked from the ground.”
“The PR people have come through here, haven’t they? Taking pictures of you and your robot lab. Mightn’t it be the case that a picture got snapped when you had that box open, and some of those PC boards visible?”
“There’s no gravity in here, Doob. I can’t leave things lying around on my desk.”
“Because,” Doob said, “obviously what’s going on here is that someone wants to talk to you through a private channel—”
“And they are proving their identity by mentioning numbers that could be known only to a few people. I get it.”
“And all I’m saying is that a really sophisticated troll would look for some detail like that, in the background of a NASA publicity photo, as a way to fool you.”
“Noted,” Dinah said. “But I doubt it.”
“Who do you think it is, then?”
“Sean Probst,” Dinah said. “I think it’s the Ymir expedition.”
Doob got a distracted look. “Man, I haven’t thought about those guys in ages.”
IT WAS STRANGE THAT A STORY AS EPIC AND AS DRAMATIC AS THE voyage of Ymir could go forgotten, but those were the times they lived in.
The ship had stopped communicating and then disappeared against the backdrop of the sun about a month after its departure from low Earth orbit (LEO) around Day 126. A few sightings on optical telescopes had confirmed that it had transitioned into a heliocentric orbit, which might have happened accidentally or as the planned result of a cont
rolled burn. Assuming it was following its original plan, Ymir should then have made almost two full loops around the sun. Since its orbit was well inside of Earth’s—the perihelion was halfway between the orbits of Venus and Mercury—it would have done this in just a little more than a year, grazing the orbit of Greg’s Skeleton—Comet Grigg-Skjellerup—a couple of hundred days ago. But this would have occurred when it was on the far side of the sun from the Earth, making it difficult to observe. The next event would have been a small matter of impregnating the comet’s core, or a piece of it, with an exposed nuclear reactor on the end of a stick, and then turning it on to generate thrust by blowing a plume of steam out the entry hole. They would have done a large “burn”—pulling out the reactor’s control blades, powering it up, and releasing a plume of steam—that would have altered the comet’s trajectory by about one kilometer per second, enough to put it on a collision course with Earth, or at least with L1, a couple of hundred days later. The timing was awkward, and many had griped about it, wondering why Sean hadn’t gone after some other comet, or plotted some other course that might have brought it home a little sooner. But people who knew their way around the solar system understood that it was near-miraculous good fortune for any comet core to be in a position to be grappled and moved in such a short span of time. The hasty shake-and-bake nature of the Ymir expedition, which had stirred up so much controversy, had been forced by the implacable timeline of celestial mechanics. Time, tide, and comets waited for no man. And even if it had been possible to bring a comet back sooner, it would have been reckless, and politically impossible. What if the calculations were wrong and the comet slammed into the Earth? So, the plan of the Ymir expedition was the only one that could have worked.
If, indeed, it were working at all. And since much of the action—the rendezvous with the comet and the “burn” of the nuke-powered, steam-fueled engine—had occurred while it was on the far side of the sun, this had been very much in doubt until a couple of months ago, when astronomical observations had proved conclusively that Comet Grigg-Skjellerup had changed its course—something that could only have happened as the result of human intervention. The comet was headed right for them. It would have triggered mass panic on Earth had Earth not already been doomed. Since then they had watched its orbit converging slowly with that of Earth, and plotted the time when it would disappear against the sun once more as it reached L1. The reactor would then have to be powered up again, as a huge “burn” would be needed to synchronize Ymir’s orbit with Earth’s and pilot it through L1 to a long ellipse that would bring it their way.
“I THINK ABOUT THEM EVERY DAY,” DINAH ANSWERED.
“When are they supposed to hit L1?”
“Any time . . . but it’s going to be a long burn, they might sort of grease it in over a period of a few days rather than trying to do one sharp impulse.”
“Makes sense,” Doob said. “One high-gee maneuver might cause the ice to break apart. When was the last time they communicated?”
“On the X band? The real radio? A few weeks after they left. Almost two years ago. But clearly they’re still alive. So it must have been radio failure.”
“Well, let’s go with that theory,” Doob suggested. “Jury-rigging a new radio that would transmit over such a distance would be kind of hopeless. The best they could hope for would be to cook something up that might work when they got closer . . . and to settle for lower bandwidth.”
“My dad used to talk about spark gap transmitters,” Dinah said. “It was a technology they used—”
“Back before transistors and vacuum tubes. Yes!” Doob said.
Dinah telegraphed down:
DOES QET SOUND LIKE AN OLD TIME SPARKY TO YOU?
Rufus returned:
YES COME TO THINK OF IT
“They took some of my robots with them,” Dinah said. “All they would have to do is jot down the MAC addresses on those units’ interface boards, and they’d have sort of a crude proof of identity. As a matter of fact . . .” and she began to pull up some of the records she had made, almost two years ago, of the robots and part numbers issued to Sean and his crew. Within a few minutes she was able to verify that the MAC address that had come in via Morse code a few minutes ago matched one on a robot that had been taken to Ymir.
“Who has access to the file you just consulted?” Doob asked, still in devil’s advocate mode.
“Are you kidding? You know how Sean is with the encryption and everything? All of this stuff is locked down. I mean, I’m sure the NSA could get in, but not some random prankster.”
“Just checking,” Doob said. “It seems awfully roundabout, is all I’m saying. Why doesn’t he just broadcast something like ‘Hey, Dinah, it’s me, Sean, my radio’s busted’? That would seem easier.”
“You have to know Sean,” Dinah said. “Look. Anything he sends out over that channel is getting broadcast to basically the entire Earth. It’s going to go up on the Internet . . . everyone’s going to know his business. He has no idea what the situation is. There’s no Internet up there and his radio’s been out for a long time. He doesn’t even know if anyone is alive up here. Or if there’s been a military coup or something. He doesn’t want to come back here if we’ve turned into the Klingon Empire.”
“I think you’re right,” Doob said. “He’s going to ease into it, test the waters.”
Forty-five minutes later Dinah was taking down a new message from QET. It started with RTFM5, then the number 00001, and went on as an apparently meaningless series of random letters.
“The only part I understand is ‘read the fucking manual,’” Dinah said, “followed by the number five.”
“Did he bring any manuals up with him?”
“He brought a bunch of stuff,” Dinah said, “from the engineers in Seattle, and left some of it here . . .”
“You have a faraway look in your eye, Dinah . . .”
“I remember asking him, ‘Why did you print that stuff out, why not use thumb drives like everyone else,’ and he said, ‘Owning your own space company brings some perks,’” Dinah said.
She found them after a few minutes’ rummaging in storage bins: half a dozen three-ring binders, volumes 1 through 6 of the Arjuna Expeditions Employee Manual. The entire stack was a foot thick.
Doob whistled. “Given the cost per pound of launching stuff into space, this is probably worth more than the Gutenberg Bible that showed up last week.”
They went straight to volume 5, which for the most part looked like any other corporate employee manual. But in between the sexual harassment policy and the dress code was a half-inch-thick stack of pages with no readable content at all. Random sequences of capital letters had been printed all over them, in groups of five, column after column, row after row, all the way down each page. Each of these pages had a different number at its top, beginning with 00001.
“This is the boy adventure secret code shit that Larz always used,” Dinah said. “But I’ll be damned if I know—”
“I’m embarrassed to say that I know exactly what this is,” Doob said. “These are one-time pads. It’s the simplest code there is—but the most difficult to break, if you do it right. But you have to have this.” And he rattled page 00001 in his hand.
Once Doob had explained how it worked, Dinah was able to begin decrypting the message by hand, but in a few minutes Doob had written a Python script that made it easy to finish the job. “I came here thinking I was going to have a drink and a chat about asteroid mining,” he said.
“Oh, stop grumbling—this is way more interesting!” Dinah said.
The message read:
TWO ALIVE. THRUSTING AT FULL POWER. SEND SITREP.
“There were six in the original crew, right?” Doob asked.
“Something must have happened,” Dinah said. “Maybe they hit a rock or something, damaged the antenna, lost some people. Maybe the radiation got to them.”
“Well, it sounds like they are coming back,” Doob said.
<
br /> “Yeah, unless—”
“Unless what?”
“Unless he just wants to hang out at L1. That would be a hell of a lot safer. I don’t think any moon shards are going to make it out that far.”
Doob reread the message.
“You’re right,” he said. “All he says is that they’re thrusting. Nothing about transferring back to low Earth orbit. Then he asks for a situation report.” He put his hands over his face and rubbed it. “I’m fading,” he announced. “I should be Skyping my family right now.”
“Get outta here,” Dinah said. “I can work on the report. And I can encrypt it, now that you showed me how it works.”
Doob pushed off and drifted to the exit, then caught himself and turned back. “I could figure this out myself,” he said, “but it’s late. Maybe you know off the top of your head. If Sean goes into that transfer orbit from L1 to here, how long before he shows up?”
“Thirty-seven days,” Dinah said.
“About seventeen days into the Hard Rain,” Doob said. “Awkward timing.”
Dinah looked back at him. She didn’t say a word, but he knew what she was thinking: If only awkward timing were the worst of our problems.
“Okay,” Doob said. “Thanks, Dinah.”
“Next time,” she said, and made a drinky-drinky motion with her thumb and pinkie.
“Next time,” he agreed, and pushed through the curtain.
Dinah checked the time. Now that she knew roughly where Ymir was, she understood the timing of the transmissions. During a certain part of each ninety-three-minute orbit, Izzy was on the wrong side of the Earth, and couldn’t receive Sean’s signal. Following each blackout period was a window during which they could talk. They had just burned a window taking down his transmission and decrypting it, and were about to go into blackout again. During that span of time Dinah should be able to write a short message and get it encrypted using the next one-time pad.
What to write wasn’t entirely clear. She could provide some obvious data like the number of arklets currently in orbit, the number of people, how many robots she had up and running. But she suspected that Sean wanted a different kind of information. He wanted to know what would happen were he to show up, thirty-seven days from now, with a mountain of ice. The Cloud Ark could use it, that was for sure. Likewise, Sean needed the Cloud Ark; two guys on a spaceship pushing a giant ball of ice was not a sustainable civilization. But Sean was going to be cagey. He was going to want something. He would want to make a deal.