Soviet Star Wars
The launch that saved the world from orbiting laser battle stations.
- By Dwayne A. Day and Robert G. Kennedy III
- Air & Space magazine, January 2010
Background: www.buran-energia.com; Foreground: Courtesy Ronald Reagan Presidential Library
(Page 3 of 5)
With such frightening scenarios in mind, the Soviet military accelerated work on the Polyus-Skif laser cannon to destroy SDI satellites. Up until then, the plan had been to use a powerful laser built by the Astrofizika design bureau. But that program had fallen behind; the Astrofizika laser and its power systems were too big and heavy for existing rockets to launch. So when Soviet engineers were told to pick up the pace on Skif, they came up with an interim plan. They would adapt a small, one-megawatt carbon dioxide laser that had already been tested on an Il-76 transport aircraft as a weapon against missiles. In August 1984, the new spacecraft was approved and designated Skif-D, the "D" standing for the Russian word for "demonstration." By January 1986, the Politburo had designated the project as one of the Soviet space program's highest-priority satellites.
Meanwhile, U.S. scientists and engineers were having their own problems with space-based lasers. As research proceeded on projects like Zenith Star, which investigated the problems of placing a two-megawatt chemical laser in orbit, the challenges of building and launching such systems became clearer. The SDI organization funded studies of particle beams and an X-ray laser that would be set off by a nuclear explosion, but none of these projects ever came close to being deployed. By 1986 the SDI leadership was shifting its attention away from orbiting lasers and toward small "kinetic kill vehicles," which could bring down enemy satellites by crashing into them.
The Soviets, though, stayed the course, and kept working on the demonstration version of their space-based laser, with a target launch date of early 1987. Engineers at the Salyut design bureau soon realized that the laser and its power system—even the smaller one already tested on an aircraft—were still too big for the Proton rocket. But a bigger launcher was in the pipeline: The Energia rocket, named after its design bureau, was being built to carry the new Buran space shuttle into orbit. Energia could carry 95 tons to space, so it could carry Skif-D. The rocket was switched. To keep costs down, engineers looked for other existing hardware to modify and incorporate, including elements of Buran and a part of the canceled Almaz military space station designated the TKS, which later became the core module of the Mir space station.
Skif-D grew into a Frankenstein's monster: 131 feet long, more than 13 feet in diameter, and weighing 210,000 pounds, more massive than NASA's Skylab space station. The complex consisted of what the Russians called a "functional block" and a "purposeful module." The functional block was equipped with small rocket engines to place the vehicle into its final orbit. It also included a power system, using solar panels borrowed from Almaz. The purposeful module carried carbon dioxide tanks and two turbo-generators to produce the laser's power, as well as the heavy rotating turret, which pointed the beam. The Polyus spacecraft was built long and thin so that it could fit on the side of the Energia, attached to its central fuel tank.
Designing a laser cannon to work in orbit was no small engineering challenge. A hand-held laser pointer is a relatively simple, static device, but a big gas-powered laser is like a roaring locomotive. Powerful turbo-generators "pump" the carbon dioxide until its atoms become excited and emit light. The turbo-generators have large moving parts, and the gas used in the formation of the laser beam gets very hot, so it has to be vented. Moving parts and exhaust gases induce motion, which poses problems for spacecraft—particularly one that has to be pointed very precisely. The Polyus engineers developed a system to minimize the force of the expelled gas by sending it through deflectors. But the vehicle still required a complex control system to dampen motions caused by the exhaust gases, the turbo-generator, and the moving laser turret. (When firing, the entire spacecraft would be pointed at the target, with the turret making fine adjustments.)
The system was complicated enough that by 1985, the designers knew that testing its components would require more than one launch. The basic Skif-D1 spacecraft structure was proved out in 1987, while the laser wouldn't fly until Skif-D2, in 1988. Around the same time, another, related spacecraft went into development. Designated Skif-Stilet (Scythian-Stiletto), it was to be equipped with a weaker infrared laser based on an operational ground-based system. Skif-Stilet could only blind enemy satellites by targeting their optics. Polyus would have enough energy to destroy a spacecraft in low Earth orbit.
Work on these projects was proceeding at a furious pace throughout 1985 when an unexpected opportunity arose. The Buran shuttle had fallen behind schedule, and wouldn't be ready in time for the planned first launch of the Energia rocket in 1986. The rocket's designers were considering launching a dummy payload instead, and Skif's designers saw an opening: Why not test some of the components of their spacecraft earlier than scheduled?
They quickly drew up plans for a vehicle that would test the functional block's control system and additional components, like the gas ejection vents and a targeting system, consisting of a radar and a low-power fine pointing laser, that would be used in conjunction with the big chemical laser. They labeled the spacecraft Skif-DM, for "demonstration model." Launch was scheduled for fall 1986, which would not affect the launch of Skif-D1, planned for the summer of 1987.