The 11D-58 engine was developed to propel
the Block-D as part of an N-1 moon program. Russia's original N-1 moon vehicle used
the Block-G to propel the lunar lander out of LEO and on a trans-lunar trajectory.
The Block-D, which uses a similar configuration, was developed to initially place the
lunar orbiter / lander into a lunar orbit and then decelerate it out onto its landing
trajectory. The Block-D was also designed to be compatible with the Proton launch
vehicle - allowing smaller probes and manned vehicles to be sent to the moon. The
Block-D was used as part of Russia's successful lunar sample return mission.
In the years that followed the race to the
moon, the 11D-58 and the Block-D were critical to Russia's planetary exploration program.
In the mid-1980's the 11D-58S was developed to serve as both the Buran OMS engines
and to power the upgraded Block-DM. The new 11D-58S uses a synthetic kerosene known
as "syntin" to increase the engine Isp from 353 to 361 seconds. Today, the
11D-58S and the Block-DM are used to serve the commercial GTO market as the third stage of
SeaLaunch (Zenit 3SL) and the fourth stage of the ILS Proton D-1-e.
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