At the same time, the countermob was stuck inside the park, blocked from confronting their opposite numbers by the same police cordon.
"If you'll let me,” I said, drawing Anton's surprised attention, “you can see what's happening on the desk screen."
I linked up the images for them. “It's a stalemate. In a few minutes, people will realize that sticking around will be just an exercise in futility. If you ask me, and with all due respect to you, it was never anything but an exercise in futility. Your city is a model of petty bourgeois life straight out of the last century—and the petty bourgeoisie frequently engages in pointless political demonstrations like this one, fueled by moral outrage, but without a focused program or plan or understanding or anything but passion. You'd be better off if you avoided them in the future."
"What's this?” Anton asked indignantly.
"It's a long story,” Penelope said. “And Victor?"
"Are you sure you want to know?"
Her shoulders sagged and she sighed. “Is it bad? Is he all right? Show me. I must know the truth."
I linked up a shot of him talking with Don Alexandro and the police commander at the top of the driveway into the residence. As we watched, Don Alexandro took Victor's hand and shook it vigorously.
"From the chatter, it sounds like he tipped off the mayor about your plans,” I said.
"Oh dear,” Penelope said, her voice slight and injured. “I think my heart is breaking."
* * * *
We were interrupted a short while later by the arrival of Captain Rivard of the Securitate, the announcement of which produced a sudden flurry of gasps, an abrupt silence, and Penelope looking stern but worried.
"What shall I do?” she asked.
"Send him up here,” I suggested. “I won't say anything, but I want a good look at him."
He was, as before, strictly formal in his demeanor and deadpan in his delivery. I wondered if he simply lacked affect, almost like a low-memory face that couldn't master inflection and nuance. Did he act like this with his wife and children and mother? Or was it a matter of training? I'd met many policemen and military officers who had learned that stiff, arms-length approach to human interaction—even a postmistress who never failed to call me “sir."
But after a few minutes, I was convinced that it was no failure of personality. Nor was it simply training and practice. Rivard had taken the basic act and morphed it into something much more sophisticated and subtle.
"I'm sorry about your difficulties this evening, senhorita,” he said. “We knew this was going to be a busy night, but we had no idea something like this could happen. I understand that nothing else was stolen or broken but the one item—and that was recovered. Is that correct?"
They knew this was going to be a busy night? Of course they did. The city had to be full of informants, every one of them all but hardwired into the Securitate. Nothing happened without their knowledge—and they needed no electronic monitoring. Nothing big or important, anyway. Not that any of that diminished Victor's betrayal.
"Yes, Captain,” Penelope said. “We've done a quick inventory, and the house insists that nothing else was touched."
"Except the house itself,” Rivard said.
"Yes,” Penelope said. “He crashed the entire system. That was how he got past the security systems."
"And his escape was foiled when he ... er ... stumbled over the gardening bots that somehow assembled in your dooryard before they broke down."
"So it would seem,” said Anton, relieving the tension that was growing between Penelope and the Securitate officer. “We were just coming down the street when we saw him fall."
"That's what the officer said,” Rivard replied. “I would like to point out to the senhorita at this point that we would have made a much quicker response to the failure of your house security system if we were not otherwise occupied."
"Occupied?” Penelope asked. “In what way?"
I almost snorted out loud. The girl was bold if nothing else. He knew where she'd been. She knew he knew, but would not admit it if she could avoid it. Was she playing him? That was a dangerous game.
"There was a demonstration at the urbamastro's Residence tonight. We had expected much, but it turned out to be a much smaller affair in the end."
"Who would be involved in such a thing?” Penelope asked, face dead calm. “Did they have a grievance?"
"We will be making the usual inquiries. But no laws were broken and no crimes were committed."
"That is good to know,” Penelope said.
"There were reports that members of the Twenty-Seven Families might be involved,” Rivard said. Not a single muscle moved involuntarily on his animatronic face.
I noticed the faintest blush of color on Penelope's cheeks, but it passed in the moment of silence following Rivard's comment.
"But that would be unlikely,” he continued. “No one in the families indulges in open politics like that."
Anton, standing in the doorway to the porch, sagged only the tiniest bit as he exhaled after holding his breath for a long minute.
"As to your case, the intruder appears to be a Mazatlan citizen of London birth. He's registered as an agent of several offworld businesses, and some of those businesses themselves are fronts for others, so it will be a while before we can determine who he is working for. It's a shame, too, that he caused all that trouble over what ultimately turns out to be a hoax."
"I beg your pardon,” Penelope asked. The color was completely gone from her cheeks now.
"I'm sorry,” Rivard said. “I should have told you sooner. The item that our burglar stole from your office, the ‘organic memory storage device'? Our records indicate that last week you and your retainers embarked on a trip to the New Palomar L-1 Solar Observatory where you obtained what was purportedly a device containing the memories of a Jonathan Bender. That's correct, isn't it?"
"Yes,” Penelope said, her gaze as blank and pitiless as the sun.
"Since your return, we have determined that the advertisement you were following up on was a fraud. There is no such thing as an organic memory storage device. The technology sounds intriguing, I am told, but no one has ever developed it. So, like your burglar, I am afraid that you have gone to a great deal of trouble for a counterfeit prize."
For a moment, I almost believed him. How could he be so thickheaded? Was everyone going to treat me like a machine?
"I see,” Penelope said. “I am terribly disappointed by this news."
Her deadpan delivery matched Rivard's perfectly.
"Now if, for example, you were to have possession of a true relic...” His voice trailed off, and we all knew that we all knew what we all knew, and that this was all was just an elaborate shadow dance.
Or would have been if Penelope hadn't forced the point.
"A true relic?"
"In the midtwenty-first century, quite a few people were recruited by medical science to cheat the deaths of their physical bodies. Some were ‘uploaded’ into massive machines—though we in Humanitas Universalis take exception to the idea that they are anything more than electronic copies of real people. Some consisted of the living brains of volunteers, encased in self-sustaining containments and connected to the world through neurotechtronic interfaces. Those are the true relics."
"Are they rare?” Penelope asked.
"They are few and far between. Many of them failed to adapt to the transition. The ones that remain are not conspicuous by their activities. Now if you were to have a true relic on your hands, it would be quite a sensation. The whole city would be tramping to your door. And we at the Securitate would take a very serious interest in such a relic and the effect it would have on our external relations. You would become a very public figure, but not to your advantage, I'm afraid. These things have a way of taking on a life of their own. Powerful forces and powerful figures would become involved. And in a community as small and as tightly wrapped as ours, you would find your freedom of movement e
xtremely limited."
We all hardened into stony silence at the unmistakable warning Captain Rivard had just given us.
Then Penelope said, “As would yours."
"As would ours,” Rivard conceded. “So my recommendation to anyone to have the fortune—good or bad—to find such a relic falling into their hands is simply this: Keep it as quiet as possible for as long as possible—and prepare for the day when it no longer is possible."
* * * *
We took Rivard's warning to heart.
After he left, Penelope and Anton and I had a long discussion of things. Of all that Rivard had said and left unsaid. We knew that he was right about one thing—we were not the kind of people who could keep things quiet forever.
Penelope proved that a few days later.
She went out one night after dark and didn't come home until well after midnight. She spent some time in the bathroom cleaning up, then came into the office.
"Aiee, I'll never be able to come in here again without putting on a bathrobe,” she said. “Are you still up?"
"I am now,” I said, but only to needle her. I'm a much lighter sleeper now that I'm so far into my second century.
"I went to Victor's tonight,” she said.
"What did he have to say?"
"Nothing. He wasn't home. That's why I went tonight."
"You're going to tell me something I don't think I want to hear, aren't you?"
"I blew up his house."
I paused for a moment to digest what I'd heard. “With explosives?” I asked.
"Anton got them for me,” she replied. “His dishonor demanded no less."
"You know, there's learning to be human and there's learning to be inhuman,” I said. “I realize it must be difficult for you. I mean you woke up a week ago Tuesday with all your brain cells suddenly connected for the first time in your life and decided that you were going to stand the world on its head before the end of the month. But mindless destruction is not a good first step. Do you really want to be the kind of woman who goes around blowing things up because her boyfriend made her unhappy?"
"No,” she said, shaking her head and sending her hair shimmering in long cascades. “I just want people to think that I'm the kind of woman who goes around blowing things up because her boyfriend made her unhappy. Even if I'm not. For now, that is necessary. Later, maybe not. And then I will want people to think something else."
I rolled my virtual eyes. Life with Penelope was not going to be easy. But it was not going to be boring.
Copyright (c) 2007 Daniel Hatch
[Back to Table of Contents]
NANOTECH ROCKET FUEL by STEPHEN L. GILLETT, PH.D.
A new rocket fuel. An SF cliché, right? Something right out of the Golden Age. And a nanotech rocket fuel could only be something devised by a clueless wannabe writer, no doubt with minimal scientific background, who's just trying to inflate their prose with the latest techie buzzword. After all, not only are all the possible fuel-oxidizer combinations now explored, but we now even have conceptual alternatives to rockets, things like skystalks and laser launching, which would be much more efficient. The problem with a rocket is that most of its energy goes into accelerating fuel that's then consumed in its turn. That's a fundamental flaw that no new fuel would solve.
Rocket fuel? Gimme a break!
Except that there just might be something to it. There's always going to be a place for rockets. Whatever their other advantages, things like skystalks and laser launchers require a lot of infrastructure on the ground. Rockets don't (or at least, they don't haveto—look at all that Golden Age SF again!). And, for safety reasons, chemically fueled rockets are going to be the only alternative for transportation off a habitable planet for the foreseeable future.
So it makes sense to make them as efficient as possible. As I described some years back ("The Ozone Rocket,” Aug 1985), the traditional measure of rocket efficiency is a parameter called “specific impulse,” I[sp]. Briefly, it's the ratio of the propellant's thrust (i.e., a force) to its propellant flow (which has dimensions of mass per second). Since in traditional (albeit sloppy) engineering practice, mass and force are both measured in pounds(1), the units of specific impulse cancel out to seconds. The hydrogen-oxygen combination used in the Space Shuttle Main Engines has an I[sp] of about 391 seconds. Some higher I[sp] combinations exist, such as by using fluorine instead of oxygen, but they have serious environmental problems. (Or, as with ozone, serious stability problems. Its extra energy comes about because it contains stored energy and wants to decompose spontaneously. That is, it's an endothermic compound: It takesenergy to make. Muchmore on this below.) You could also, in theory, squeeze out a few more seconds of I[sp] by mixing something light into the hydrogen that reacts even more enthusiastically with oxygen—lithium, for example. That's another notion we'll return to later.
[FOOTNOTE 1: Yes, a pound is a unit of mass, not just in everyday engineering practice but in law. In 1893 the National Bureau of Standards defined the standard avoirdupois pound as 1/2.20462 kilogram. By a 1959 agreement among the English-speaking nations, the conversion was revised to one pound = 0.45359237 kilos exactly, an adjustment of about one part in ten million. This remains the legal definition of the pound to this day.]
But it turns out other performance metrics can even be more important than I[sp]. Sure, ceteris paribus, you want the highest I[sp] you can get, but ceterisisn't usually paribus. You need to also minimize the overhead of the rocket itself: the dead weight of tankage and plumbing that doesn't contribute to payload capacity. Minimizing that burden is harder with some fuels than others. Other things being equal, for example, denser propellants are better, because they need smaller tanks.
The complexity of the plumbing is another source of dead overhead. A conventional liquid-fueled rocket is a bipropellantsystem. It requires two separate, parallel systems for fuel and oxidizer: two sets of pumps and pipes and intricate engineering to bring them all together properly.
Just one propellant would be much simpler. Of course, solid-fueled rockets already do this, all the way from the hobby rocket fueled with gunpowder to the Shuttle's SRBs (Solid Rocket Boosters). In fact, solid-fueled rockets require no plumbing at all—a major mass saving! But we also all know, because of their absence of plumbing, that solid-fueled rockets have the gross disadvantage of not being throttle-able. This is a long-standing problem with the SRBs on the Shuttle. You can't change your mind—you don't even have much control—after they're ignited. Once the candles were lit, the Challenger, twenty years ago, was doomed—even if someone had seen the flame leaking from the SRB joint, nothing could have been done about it.
So what we really want is a dense liquid monopropellant. Can nanotechnology help us here?
Probably. And in a couple of ways: First, in the synthesis of high-energy molecules whose present syntheses are at best expensive and at worst nonexistent. And second, in the engineering of reasonably stable molecular mixtures of fuel and oxidizer that could act as monopropellants. Indeed these applications are mostly proto-nanotech, involving no molecular-level machines or anything like that, so they might even be fairly near term.
Let's look at some of the issues.
* * * *
The Virtues of Instability
Obviously, the monopropellant must contain stored energy. Lots of stored energy, in fact—as much as possible. In turn, this fundamentally means there has to be a more stable arrangement of the constituent atoms than that in the propellant itself. Obviously, then, there must be big barriers to premature reaction! Nonetheless, monopropellants are intrinsically less safe than bipropellants. They want to “go downhill” and release the excess energy, and we just have to deal with it.
The simplest example of a monopropellant is a mechanical mixture of a fuel and an oxidizer. Ordinary black powder—sulfur, saltpeter (potassium nitrate, KNO[3]), and charcoal (carbon)—is the classic example. When black powder ignites, the oxygen in the nitrate oxidizes the carbon a
nd sulfur. And it's well known that gunpowder doesn't take much to set off, even though it doesn't explode spontaneously at ordinary temperatures. Note, too, that the individual components of gunpowder are perfectly stable by themselves. It's their reaction with each other that makes the explosion.
This is not true for ammonium nitrate, NH4NO3 or “AN.” Like the other nitrates, it's an “ionic salt.” The crystal consists of alternating layers of the positively charged ammonium ion (NH4+) and the negatively charged nitrate ion (NO3—), the whole structure sticking together by its mutual electrostatic attraction. However, there is a difference: The hydrogens in the ammonium ion would really rather be with the oxygens in the nitrate. In other words, the reaction:
(Rxn 1) 2 NH[4]N[3] (right arrow) 2 N[2] + 4 H[2]O + O[2] + 237.0 kilojoules per mole (kJ/mol)(2)
yields energy(3). Lots of energy, in fact.
[FOOTNOTE 2: I'm using the heat of formation (enthalpy), by the way, rather than the more correct Gibbs free energy. It's a more accessible number, and for these compounds there isn't much difference.]
[FOOTNOTE 3: Actually, if you gently heat AN you get nitrous oxide, N[2]O, instead of N[2] and O[2]. That's a common lab-scale preparation.]
The reason AN is pretty inert at ordinary temperatures is simply because it requires a lot of energy input to break down the ammonium and the nitrate so that their hydrogen and oxygen can react with each other. Or, in chem speak, it has large “kinetic barriers” to reaction. In fact, that's what we need for any endothermic compound or mixture to be reasonably inert under ordinary conditions. After all, gasoline and air can sit around indefinitely, too: You have to input energy (what a chemist calls the “activation energy") to overcome the reaction barriers.
Like a gasoline/air mixture, AN does react when heated, though, and if really mistreated it can explode. In 1947 much of Texas City, a port on the Gulf Coast near Galveston, was leveled by an enormous explosion when a docked ship containing AN blew up. The ship, with a cargo of some 17 million pounds of NH[4]NO[3], had caught fire, and the build-up of heat under sealed hatches caused catastrophic decomposition. Some six hundred people were killed, and the explosion is estimated to have been equivalent to 2-4 kilotons of TNT—quite possibly the largest chemical explosion ever. (Why was the ship carrying so much AN? It's an excellent fertilizer as it contains highly soluble nitrogen in two different chemical states. The cargo was to be shipped to postwar Europe.) Since then, other catastrophic explosions have happened over the years, though fortunately none so devastating. Procedures for dealing with AN safely in ton lots, a direct result of the Texas disaster, have worked well overall.
Analog SFF, October 2007 Page 7
