Europa Strike(88)
At the moment, however, a larger portion of Chesty’s mind was focused on the input from a number of optical sensors mounted on the twenty-meter, spindly-framework jury-rig wrapped in superconductor cable and pointed, with the front end lifted off the ice by cables attached to the A-frame, toward the southwest. The alignment had to be perfect, and Chesty had labored carefully for the past twenty hours with a Marine working party under Kaminski’s direction, figuring out the theta—the angle between the cable-wrapped microwave tower and the surface—to an accuracy of a part or two in a hundred thousand. That level of accuracy was almost impossible to achieve even with the proper tools. What they’d accomplished here, with few tools beyond military laser sights adapted to the effort and human muscle power, had been startlingly impressive, the result of trial and error, with calculations so fussy that Chesty had been forced to take into account the slight expansion in the supporting cables as the sun came out from behind Jupiter and warmed them by a handful of degrees. When the time came, he would be able to fine-tune the trajectory by slightly increasing or decreasing the power he fed to the SC cables; the really critical adjustments were made by shifting the back end of the tower back and forth on the ice in centimeter increments, aligning the muzzle with a laser beacon on the crater rim 215.7 meters away. The survey data for the placement of that beacon had come from a careful photometric analysis of photographs relayed to Earth by the Farstar deep space telescope, which had managed to pinpoint—to within a few tens of meters—the precise location of the Chinese LZ at Asterias Linea.
The principles of railguns—magnetic linear accelerators—were well known. The first prototype had been built in 1937 by Edward Fitch Northrup, an eccentric inventor who’d worked out the details in a work of fiction. Electricity fed through the superconducting coils generated an intense, fast-moving magnetic field which could be pulsed to increase acceleration. The math involved was trivial; the most uncertain elements in the equation, as always, had to do with human uncertainties.
The Marines had just finished loading the cannon. The round—another canister, this one wrapped tightly with superconducting cable attached to a small fuel-cell power generator inside—floated now in the magnetic grasp of the makeshift linear accelerator. Inside, fifty-five grams of antimatter rested in magnetic suspension inside an A-M carry sphere. The power feed had been carefully packed with foam to let it withstand the sudden shock of ultra-high G acceleration; the trigger was a simple two-stage switch armed by one shock exceeding 100 gravities and fired by a second. The round should arm itself when fired; on impact, the magnetic suspensor field in the A-M containment sphere would fail, and fifty-five grams of antimatter would instantly annihilate fifty-five grams of matter, liberating some 1010 joules of energy, roughly equivalent to two thousand tons of high explosive—about the same punch as the bomb that destroyed Hiroshima.
“Everything is ready for firing,” Chesty announced to the personnel gathered in C-3. He could tell from their heart rates and breathing, from the pitch of their voices as they made jokes with one another, that they were all nervous.
Understandable. If something went wrong, a rather large crater would suddenly appear uncomfortably close to the E-DARES facility—within a couple of kilometers, in fact. That was entirely too close to ground zero for a base anchored to the face of an ice cliff.
“Thank you, Chesty,” Jeff said.
“I suggest that you give orders to move all surface personnel well back from the cannon,” Chesty added. “We have no way of predicting what the recoil effects might be.”
“Already taken care of, Chesty. Wait one.”
He waited.
Kaminski
C-3, Ice Station Zebra, Europa
2045 hours Zulu
Frank Kaminski was holding his breath. The idea had not been original, but if this thing didn’t work, he was going to be the one responsible. Antimatter was such damnably touchy stuff. Any mistake, any mistake, and they would end up shooting themselves in the foot. There might not be much left for the Charlies to come in and take over.
In 1900, forty-nine U.S. Marines had been part of the mix of foreign troops defending the Foreign Legation Quarter in Beijing—then Peking—during the Boxer Rebellion, as the “Society of Heavenly Fists” had attempted to oust all foreign influences from China. During the five-week siege that followed, Chinese Christians digging a trench discovered an old Anglo-French rifled cannon abandoned in the compound during the expedition of 1860. The Marines had excavated the barrel and cleaned it up; Italian troops provided a gun carriage. Russian nine-pound shells that had been dumped in a well earlier to keep them out of Boxer hands were fished out, dried off, and found to fit the gun—not perfectly, but close enough, though they had to be taken apart and loaded in two pieces through the muzzle. Despite the makeshift uncertainties, the weapon had acquitted itself well throughout the siege. The Marines had called the hybrid monster “The International Gun.”