The Indian Space Research Organisation (ISRO) has
achieved a major milestone in the development of rocket
systems for satellite launches. ISRO successfully hot
tested the cryogenic upper stage for geosynchronous
launch vehicle (GSLV) on 28th October for 50 seconds
at the liquid propulsion systems centre (LPSC) test
complex at Mahendragiri. The first of its kind test
in India, the performance was as predicted.
has taken up indigenous development of cryogenic stage
with regenerative cooled engine, which produces a thrust
of 69.5 kN in vacuum, to replace the existing procured
stage from Russia currently used in GSLV flights.
part of this effort, the cryogenic engines have been
realised and tested earlier for a cumulative duration
of 6000 seconds.
the stage level hot test all stage elements like engine,
insulated propellant tanks, booster pumps, fill and
drain systems, pressurisation systems, gas bottles,
igniters, cold gas orientation and stabilisation system
and others worked as per the actual flight standards
stage uses the cryogenic propellants namely liquid hydrogen
at -250º C and liquid oxygen at -196º C. The
turbo pumps used for drawing the propellant from the
tanks operate at the very high speed of 42,000 rpm.
materials used to operate at cryogenic temperatures,
chilling processes, interplay of various critical engine
parameters and a host of other technical aspects make
the development of cryogenic stage a very challenging
Indian industries have significantly contributed in
the realisation of the cryogenic stage. This hot test
has demonstrated the design adequacy and performance
of the integrated flight system, further tests for this
flight unit are planned to validate robustness of the
After completion of the qualification tests, the indigenous
cryogenic stage is planned to be flight tested in GSLV-
D3 mission next year.