The original Blok Zh was heavily modified and stretched to increase the propellant load by about half for an upgraded 8D715K engine. With this new information in hand, the direct ascent technique was abandoned in early 1959 and a new, larger variant of the 8K78 (eventually known as the Molniya) was hurriedly developed. This technique, which was discovered independently by American scientists and engineers, has a number of advantages over the direct ascent technique: launch windows are longer and more flexible, the accuracy requirements for the launch vehicle are relaxed, and gravity losses are reduced allowing more payload to be sent beyond the Earth. After coasting for a time, the escape stage would ignite at the optimum ejection point to send the payload on its escape trajectory. Instead of a continuous powered ascent where the payload is hurled directly into an escape trajectory to the Moon or beyond, an escape stage with the payload attached would first be placed into a temporary parking orbit around the Earth. This much improved launch vehicle could send probes with masses as large as 400 to 500 kilograms to Venus or Mars via a direct ascent trajectory of the type used by the first Luna probes.īut by the end of 1958, theoretical studies had discovered a better method for reaching the Moon and planets beyond. This tapered upper stage used a four-chamber 8D715 engine developed by OKB-154 burning kerosene and LOX to generate nearly 295 kilonewtons of thrust. The Blok Zh was a modified second stage from an R-9A ICBM or 8K75 (eventually known by the NATO designation, SS-8 Sasin) then under development at OKB-1. In the original studies for the 8K78, a Blok Zh upper stage would be fitted to the R-7A. In addition to a laundry list of improvements to the avionics, structure and operations, the 8K74 sported upgraded RD-107/108 engines which generated 4,020 kilonewtons of thrust at liftoff. The first stages of the 8K78 would be based on the improved R-7A ICBM or 8K74 then under development. (RKK Energia)ĭuring 1958 plans were developed for a much-improved launch vehicle designated the 8K78. Later this stage was enlarged to become the Blok I stage. The second stage of the R-9A ICBM was the basis of the Blok Zh upper stage in the original 8K78 proposal. An upgraded version of this rocket called the 8K72K was also under development to launch the Soviet Union’s first manned spacecraft, Vostok. The 8K72 that was used to launch the first Luna probes was an R-7 with a small upper stage added called Blok E. The rocket that launched the first Sputniks, the 8K71PS, was simply a stripped down version of this ICBM. The RD-108 also ran at a lower thrust level so that it could operate up to 210 seconds longer than the boosters’ RD-107 engines and its nozzles were optimized for operation at high altitudes. The major external difference between the RD-107 and 108 was that they incorporated two and four small gimbaled vernier engines, respectively, to steer the R-7 and trim its velocity. The RD-107/108 consisted of a single turbopump assembly feeding a cluster of four fixed combustion chambers. These engines were designed and built by OKB-456 under the direction of Valentin Glushko. The core used an engine of similar design called the RD-108. A single turbopump assembly provide propellant to four large thrust chambers and two smaller vernier engines used to steer the rocket.Įach booster of the R-7 was powered by an RD-107 engine that used kerosene and liquid oxygen (LOX) as propellants. Pictured here is the RD-107 engine used to power the four boosters of the R-7 rocket. Even as the first probes were launched towards the Moon, Soviet scientists and engineers under Korolev’s direction were already busy developing the hardware needed to reach the nearest planets. The focus of most of the space activity in the Soviet Union during these early years was at the design bureau designated OKB-1 (the Russian acronym for Experimental Design Bureau 1) run by the legendary Soviet space engineer, Sergei Korolev. And once the first Soviet Luna and American Pioneer probes had reached the Moon in 1959, the next logical targets were the planets. Just months after the launch of the first satellites around the Earth, ambitious space scientists and engineers, as well as national leaders, set their sights on the Moon. With the beginning of the Space Age, we finally had at our disposal the technology needed to explore the worlds beyond the Earth at close range. But just over half a century ago, a mission to Mars was only a dream and the planets, along with a host of minor solar system bodies, were distant, poorly understood places at best. Today we have a veritable fleet of spacecraft from nations around the globe studying Mars from orbit and its surface.
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