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INSAT-3A Launched
April 10, 2003

The multipurpose satellite, INSAT-3A, built by ISRO, was successfully
launched early this morning (April 10, 2003) by the Ariane-5 launch
vehicle of Arianespace. INSAT-3A is the third satellite in the
INSAT-3 series; INSAT-3B and INSAT-3C were launched by Ariane-5 and
Ariane-4 launch vehicles on March 22, 2000 and January 24, 2002
respectively. 

The 160th flight of Ariane, carrying ISRO's 2,950 kg INSAT-3A and
GALAXI-XII of US, lifted off at 4.22 am IST from Kourou, French
Guyana. INSAT-3A was injected into a Geosynchronous Transfer Orbit
(GTO), 30 minutes after the lift-off in 3-axis stabilized mode, with
a perigee (nearest point to earth) of 859 km and an apogee (farthest
point to earth) of 36,055 km and an inclination of 1.99 deg. with
respect to the equator. The satellite is at present going round the
earth with an orbital period of about 10 hours 47 minutes.

The Master Control Facility (MCF) at Hassan in Karnataka acquired the
telemetry signal from INSAT-3A at 04.52 am IST. The initial health
checks on the satellite indicate that the performance of the
satellite is normal. First operations on the satellite were carried
out by issuing commands from the MCF. The outermost panel of the
stowed solar array of INSAT-3A was oriented towards the Sun to start
generating the electrical power required by the satellite.
Subsequently, the earth viewing face was oriented towards the earth
and calibration of the gyros on board the satellite was carried out.

INSAT-3A is being tracked, monitored and controlled from MCF. During
the initial phase of INSAT-3A operations, 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) ground stations.

In the coming days, orbit raising operations of INSAT-3A will be
carried out by firing its 440 Newton Liquid Apogee Motor (LAM) in
stages till the satellite attains its final geostationary orbit,
which is about 36,000 km above the equator. The satellite has about
1.6 tonne of propellant (Mono-Methyl Hydrazine - MMH fuel and Mixed
Oxides of Nitrogen - MON-3 oxidiser) for orbit raising operations as
well as for station keeping and in-orbit attitude control. The
on-orbit propellant availability will enable maintaining the
satellite for operational services for a period of 12 years. 

When the satellite reaches near-geostationary orbit, deployment of
its solar panels and the two antennas as well as the solar sail will
be carried out and the satellite put in its final 3-axis stabilised
mode. This will be followed by trim manoeuvres to take the satellite
to its designated orbital slot. The payloads will be subsequently
checked out before the commissioning of the satellite.

INSAT-3A will be positioned at 93.5 deg East longitude in the
geostationary orbit. Other INSAT satellite locations are: INSAT-2DT
at 55 deg East longitude, INSAT-2E and INSAT-3B at 83 deg East
longitude, INSAT-3C and KALPANA-1 at 74 deg East longitude.

INSAT-3A has the main body in the shape of a cuboid of 2.0 x 1.77 x
2.8 m. When its solar panel and solar sail are fully deployed in
orbit, the satellite will measure 24.4 m in length. INSAT-3A's Sun
tracking solar panels generate 3.1 kW of power. Two 70 Ah
Nickel-Hydrogen batteries support full payload operations even during
eclipses. INSAT-3A, like all its predecessors in the INSAT series, is
a 3-axis body-stabilised spacecraft using earth sensors, sun sensors,
inertial reference unit, momentum/reaction wheels and magnetic
torquers. It is equipped with bi-propellant thrusters. The satellite
has two deployable antennas and one fixed antenna that carry out
various transmit and receive functions. 

INSAT-3A Communication Payloads comprise:

12 C-band transponders, nine of which have expanded coverage
providing an Edge-of-Coverage (EoC) Effective Isotropic Radiated
Power (EIRP) of 38 dBW and other three having India coverage beam
providing an EoC-EIRP of 37 dBW. Six upper extended C-band
transponders having India beam coverage providing an EoC-EIRP of 37
dBW. Six Ku-band transponders having India coverage beam providing an
EoC-EIRP of 47.5 dBW and A Satellite Aided Search & Rescue (SAS&R)
transponder. The Meteorological Payloads include:

Very High Resolution Radiometer (VHRR) with 2 km resolution in the
visible spectral band and 8 km resolution in infrared and water
vapour bands. Charge Coupled Device (CCD) camera operating in
visible, near infrared and shortwave infrared bands with 1 km
resolution. Data Relay Transponder (DRT) INSAT-3A is expected to
augment the present INSAT capacity for communication and
broadcasting, besides providing meteorological services along with
INSAT-2E and KALPANA-1. 

With ISRO Satellite Centre (ISAC), Bangalore, as the lead Centre,
INSAT-3A 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-3A. MCF
is responsible for initial and in-orbit operation of all
geo-stationary satellites of ISRO.

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