GSLV-F08 mission carrying the 2-tonne class
GSAT-6A communication satellite will open
a new chapter for the Indian Space Research
Organisation.
With an eye firmly on the “all-important”
Chandrayaan-2, the space agency is trying
out a few critical components, which include
induction of high-thrust Vikas engine and
electromechanical actuation system in place
of electrohydraulic actuation in the rocket’s
second stage.
The next generation Vikas engine developed
by the Liquid Propulsion Systems Centre (LPSC)
is being flown for the first time.
LPSC director V Narayanan told Express that
the improved engine would give a significant
advantage in terms of enhancing payload capability.
“Usually, the chamber pressure is 58 bar,
but with the use of high-thrust Vikas engine,
we will achieve 62 bar, which is a 6% increase
in thrust that gives us 70 kgs of additional
payload gain in this mission.
Right now, we are going to use the high-thrust
Vikas engine only in the second stage.
Basically, we are validating it.
For Chandrayaan-2 mission, we will be using
five such engines aiming for a payload gain
of around 250 kgs,” Narayanan said.
Another important experiment that the national
space agency is attempting is last depletion
mode shutdown.
Generally, scientists store extra propellant
in the tank and cut off the upper cryogenic
stage after reaching desired velocity.
However, this time they are attempting to
deplete the liquid oxygen, which means using
up another 60-70 kgs of propellant in order
to achieve 4-5 seconds of additional burn
duration.
Narayanan said this would be the best way
of mission planning and optimum utilisation
of propellants.
“All these new things are being done keeping
lunar mission in the mind and ISRO’s bigger
game plan to increase GSLV payload capability.
For Chandrayaan-2, we are formulating a perfect
combination.
The four strap-ons and second stage will be
boosted with high-thrust Vikas engines; cryogenic
upper stage will be loaded with enhanced propellants
of 15 tonnes instead of current 12.8 tonnes
and will be operated with 9.5 tonne thrust
compared to the present 7.5.”
ISRO chairman K Sivan told Express that the
high-thurst Vikas engine has been under development
for the past three years and is robust.
It has cleared several tests, he said.
“It was developed as part of ISRO’s plans
to have GSLV launches with heavier payloads.
GSLV Mk 2 and GSLV Mk 3, when stabilised,
will have huge international demand.
”On introduction of electromechanical actuation
system in place of electrohydraulic actuation
in the second stage of the rocket, Sivan said
the new system is simpler and more robust,
which increases the vehicle’s reliability.
The GSLV-F08 launch is scheduled from the
second launch pad at Satish Dhawan Space Centre,
Sriharikota at 4.56 pm.
It is the 12th flight of GSLV and sixth flight
with indigenous Cryogenic Upper Stage.
The payload GSAT-6A is a high power S-band
communication satellite.
It will be India’s second predominantly
S-band communications satellite — the first
being the GSAT-6.
It will complement GSAT-6, which has been
orbiting Earth since August 2015.
The purpose of the satellite is to provide
a platform for developing technologies such
as demonstration of 6m S-Band ‘Unfurlable
Antenna’, handheld ground terminals and
network management techniques.
These are useful in satellite-based mobile
communication applications.
According to Liquid Propulsion Systems Centre
director V Narayanan, the Chandrayaan-2 mission
will see use of five next generation Vikas
engines.
“We are aiming for a payload gain of around
250 kgs,” he said.
Salient features of Satellite
1.
Provides mobile communication for India through
multi-beam coverage facility.
2.
6m diameter unfurlable antenna for use communication
link.
3.
0.8m fixed antenna for hub communication link.
