Free A Tall Tail by Charles Stross Page B

liquid fluorine is not your friend. Fluorine is the most active elemental oxidizing agent in the periodic table, and liquid fluorine makes liquid oxygen look inert and unreactive. It likes to oxidize things we don’t usually think of as oxidizable, like water—which it reacts with to product hydrofluoric acid, which is in turn nasty enough that sane people avoid working with it because if you forget for one second what you’re dealing with it’s liable to dissolve your bones.
    Back in the nineteenth century, chemists used to joke that you could tell who had just discovered elemental fluorine by reading the obituary columns. But liquid fluorine and hydrofluoric acid are themselves not the worst oxidizing agents out there. Elemental fluorine may be the thuggish hit-man of the halide world, but if you torment it with chloride ions you can turn it into the chemical equivalent of Hannibal Lecter: chlorine trifluoride, an oxidizing agent so malignant that it will set fire to water and burn explosively on contact with sand, asbestos, or rocket scientists.
    Jim Benford smiled. “Now why don’t you tell him about the proposal for NAIL SPIKE?”
    â€œWhat?” Leonard looked confused for a moment. “I thought he’d be more interested in D-SLAM—”
    â€œWasn’t that Project PLUTO?” I asked. I’m enough of a crazy cold war projects geek to have heard of the atomic powered cruise missile—a device that only Dr. Strangelove could have loved—from the 1960s.
    â€œYes, D-SLAM was PLUTO,” said Jim. “But it’s not that interesting, unless you want a power source for a drone that can explore the atmosphere of Jupiter for years at a time. NAIL SPIKE, on the other hand—”
    â€œNAIL SPIKE was a CIA project.” Leonard polished off his cocktail and put the glass down on the bar, just loudly enough to get my attention. He caught my eye. I sighed, and waved at the bartender.
    â€œAre you supposed to be talking to me about it, then?” I asked. “Me being a foreigner, remember?” Not that I wasn’t curious, but I wasn’t particularly enthusiastic about unintentionally having my stay in the US extended by a few years due to someone else’s loose lips.
    â€œOh, it’s old hat.” Jim waved my question away. “We’re talking about 1970s projects here. It was declassified in the 90s, after the end of the cold war.”
    â€œThe CIA were into rocketry?” I couldn’t help myself.
    â€œAfter a fashion.” Our new round of drinks arrived. Leonard took a cautious sip of his. “Who was that writer friend of yours, Jim, from California…?”
    â€œLarry, Larry Niven. ‘Any reaction motor is a weapon of efficiency proportional to its efficiency as a rocket.’ That’s what you were thinking of?”
    â€œYes, that’s the one. He was spot-on, you know. NAIL SPIKE was about building a really efficient rocket motor and then marketing it to the opposition.”
    â€œWait, what?” (I can’t easily describe the experience of involuntary nasal irrigation with a lime margarita, so I won’t bother. Just try not to do it.)
    When I stopped convulsing Leonard continued: "The idea is quite simple. During the 1940s and 1950s we experimented with a number of really quite unpleasant substances before settling in the 1960s on a handful of slightly less unpleasant stuff as our propellants of choice—liquid oxygen, liquid hydrogen, kerosene, and solids based on powdered aluminum. Of course, there were exceptions; Titan ran on dinitrogen tetroxide and a hydrazine/UDMH mixture, for example. Hydrazine isn’t just explosive, it’s corrosive and poisonous too. There’s a reason the EPA-bullied wimps at NASA won’t use it for launch vehicles these days. Dinitrogen tetroxide is explosive and corrosive. But we more or less stopped using really nasty stuff like red fuming