Ikar (rocket stage)

Ikar was a Russian rocket upper stage introduced by TsSKB Progress in 1999 for use with the Soyuz-U rocket. It was derived from the propulsion module that had flown on more than 30 Yantar reconnaissance satellites, so it reused existing equipment and needed only changes to its command and control systems and its mechanical and electrical interfaces with payloads. The stage weighed 820 kilograms, sat beneath the payload fairing and could restart in flight up to 50 times, which let it release several satellites into different orbits. It was powered by an S5.144 engine with a vacuum thrust of 2.943 kilonewtons plus 16 vernier thrusters, burning unsymmetrical dimethylhydrazine with dinitrogen tetroxide. Ikar was used on six launches in 1999, each carrying four Globalstar satellites, before the improved Volga stage replaced it. This entry rests on one encyclopedia article; a second independent source is owed.