The
401 tonne, 49 m tall GSLV, carrying an experimental, 1540 kg, satellite,
GSAT-1, lifted off from Sriharikota at 3-43 pm IST. Seventeen minutes
after lift off, GSAT-1 was successfully placed in an orbit of 181 km perigee
and an apogee 32, 051 km with the orbit inclination of 19.2 degree with respect
to the equator. The injection of the satellite into orbit occurred about 5000
km from the launch centre.
It may be recalled that the first launch attempt of GSLV was aborted one second
before the lift-off on March 28, 2001 by the Automatic Launch Processing System
(ALS) after it detected that one of the strap-on boosters did not develop the
required thrust. After detailed analysis, the exact reason was identified,
recovery operations were completed in 18 days and the vehicle was made ready
for re-launch.
The count-down commenced 57 h 49 m prior to lift-off, i.e., 5:56 am on April 16,
2001. The count-down activities like filling of fuel for second stage and the
four strap-on motors, arming of pyros, movement of Mobile Service Tower,
filling of cryostage and electrical checks were done smoothly. After station
checks, on all mission elements, the authorization for the mission was given at
16 minutes before lift-off. The Automatic Launch Processing System took over at
12 minutes before lift-off.
As the count down for the launch proceeded, at 4.6 seconds before the count
zero, the four liquid propulsion strap on stages, each carrying 40 tonne of
propellant, were ignited. After confirming the normal performance of the liquid
propulsion strap-on motors, the whole system was released one second before
lift-off and at count zero, the mammoth 125 tonne solid propellant first stage
motor was ignited and GSLV blazed into the evening sky. The first stage burned
for 100 seconds while the liquid propulsion strap on stages continued thrusting
up to 162 seconds from lift-off taking the vehicle to an altitude of 75 km. At
the end of the first stage burn out the GSLV had reached a velocity of 2.63 km
per second.
The second stage, which carried 37.5 tonne of liquid propellant, ignited 1.6
seconds before the burn out of the first stage strap-on motors. This stage
burned for 147 seconds taking the vehicle to an altitude of 126 km and
increasing its velocity to 5.18 km per second. During the second stage
operation, when the vehicle was at an altitude of 116 km and thus cleared the
dense atmosphere, the heat shield that protects the spacecraft from the
aerodynamic heating, was discarded.
After the separation of the second stage at 314 seconds from lift off, the
cryogenic stage was ignited. The cryogenic stage, which carried 12.5 tonne of
liquid hydrogen and liquid oxygen burned for 693 seconds taking the satellite
and vehicle equipment bay to an altitude of 195 km and increasing the velocity
to 10.17 km per second as required for placing the satellite in the
geostationary transfer orbit. The stage which was procured from Russia and
interfaced with ISRO developed electronics, was separated from the spacecraft
at about 1036 seconds from lift off at an altitude of 202 km about 5000 km from
the launch pad at Sriharikota. After the spacecraft separation, the cryogenic
stage was reoriented to avoid any collision with the satellite and passivated.
All through the flight, the vehicle was guided by the inertial navigation and
guidance systems. The performance data of the GSLV was tele-metered to the
ground stations in Sriharikota, Port Blair and stations at Brunie and Biak in
Indonesia which were networked with SHAR Centre.
The first signals acquired from the GSAT-1 indicate normal performance of the
satellite. Further operations like orbital manoeuvres to take the satellite
from the geosynchronous transfer orbit to its final geostationary orbit at
36,000 km using the on board apogee motor and deployment of its appendages like
solar array, solar sail and the antenna, GSAT-1 will be carried out in the
coming days. GSAT-1 carrying three C-band transponders and one S-band
transponder, will be used for conducting communication experiments like digital
audio broadcast, internet services, compressed digital TV transmission. Several
new spacecraft elements like improved reaction control thrusters, fast recovery
star sensors and heat pipe radiator panels are also being tested on this
satellite.
The successful accomplishment of GSLV-D1/GSAT-1 Mission is the culmination of a
decade of efforts of ISRO Centres' in design and development and supported by
several educational and academic as well as R&D institutions in the
country. Many of the GSLV hardware including motor cases, inter-stages, heat
shield, engine components, electronic modules are manufactured by the Indian
industry. About 150 industries, both public and private sectors are involved.
GSLV is the most technologically challenging mission undertaken so far under the
Indian space programme. It is the culmination of efforts of a large number of
scientists, engineers and technicians, over the last ten years. The mission
heralds a significant milestone towards the establishment of indigenous
capability for launching communication satellites like INSAT. Having already
established indigenous capability for launching IRS class of remote sensing
satellites through PSLV, the launch of GSLV makes the Indian space programme
even more self-reliant while tuning the programme towards national development.