satellite built by ISRO, was successfully launched early this morning (January
24, 2002) by the Ariane-4 launch vehicle of Arianespace. The 147th flight of
Ariane, carrying ISRO's 2,750 kg INSAT-3C, lifted off at 05:17 am IST from
Kourou, French Guyana in South America. INSAT-3C was injected into a
Geo-synchronous Transfer Orbit (GTO), 21 minutes after the lift-off, in a
3-axis stabilised mode, with a perigee of 570 km and an apogee of 35,920 km and
an inclination of 4 deg. with respect to the equator. The satellite is at
present going round the earth with an orbital period of about 10.5 hours.
The INSAT Master Control Facility (MCF) at Hassan in Karnataka acquired the
telemetry signal from INSAT-3C at 5:47 am IST. The initial health checks on the
satellite indicate that the performance of the satellite is normal. First
operations on this satellite were carried out by issuing commands from the
Master Control Facility (MCF) at Hasssan. The outermost panel of the stowed
solar array on the south side of the satellite was oriented towards the sun to
start generating the electrical power required by the satellite during its
transfer orbit phase. Subsequently, the earth viewing face was oriented towards
earth and calibration of the gyros on board the satellite has been carried out.
INSAT-3C is being tracked, monitored and controlled from MCF, Hassan. During the
initial phase of the operation, MCF also utilises INMARSAT Organisation's
ground stations at Beijing (China), Fucino (Italy) and Lake Cowichan (Canada).
The satellite's orbit is being precisely determined by continuous ranging from
the participating Telemetry Tracking and Command (TTC) stations.
In the coming days, orbit raising operations on INSAT-3C will be carried out by
firing the 440 Newton liquid apogee motor on board in stages till the satellite
attains its final geo-stationary orbit, about 36,000 km above the equator. The
satellite has about 1.5 tonne of propellant (Mono-Methyl Hydrazine - MMH and
Mixed Oxides of Nitrogen - MON-3) for orbit raising operations as well as for
station keeping and in-orbit attitude control. The on orbit fuel availability
will enable maintaining the satellite for operational services for a period of
When the satellite reaches near geo-stationary orbit, deployment of the two
solar panels and the two antennas will be carried out and the satellite put in
its final 3-axis stabilised mode. The payloads will be subsequently checked out
before the commissioning of the satellite.
INSAT-3C will be co-located with INSAT-1D at 74 deg East longitude. Other INSAT
satellite locations are: INSAT-2C and INSAT-2B at 93.5 deg East longitude,
INSAT-2E and INSAT-3B at 83 deg East longitude, INSAT-2A at 48 deg East
longitude and INSAT-2DT at 55 deg East longitude.
INSAT-3C carries 24 C-band transponders, six extended C-band transponders, two
S-band transponders and a Mobile Satellite Service transponder operating in
S-band up-link and C-band down link.
INSAT-3C has the main body in the shape of a cuboid of 2 X 1.7 X 2.8 m. When the
two solar panels are fully deployed in orbit, it will measure 15.5 m in length.
The sun tracking solar panels generate 2.75 kW of power. Two 60 Ah
Nickel-Hydrogen batteries support full payload operations even during eclipses.
INSAT-3C, like all its predecessors in the INSAT series, is a 3-axis
body-stabilised spacecraft using momentum/reaction wheels, earth sensors, sun
sensors, inertial reference unit and magnetic torquers. It is equipped with
unified bi-propellant thrusters. The satellite has two deployable antennas and
three fixed antennas that carry out various transmit and receive functions.
INSAT-3C is the second satellite to be launched in the INSAT-3 series. The first
satellite, INSAT-3B, was launched on March 22, 2000. INSAT-3C is expected to
augment the present INSAT capacity for communication and broadcasting, besides
providing continuity of the services of INSAT-2C when it reaches the end of
mission life late this year.
With ISRO Satellite Centre (ISAC), Bangalore, as lead centre, INSAT-3C was
realised with major contributions from Space Applications Centre (SAC),
Ahmedabad, Liquid Propulsion Systems Centre (LPSC) at Valiamala and Bangalore,
Vikram Sarabhai Space Centre (VSSC) and ISRO Inertial Systems Unit (IISU),
Thiruvananthapuram. Besides, several industries in both public and private
sectors have contributed to the realisation of INSAT-3C. MCF is responsible for
initial and in-orbit operation of all geo-stationary satellites of ISRO.