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Rediff.com  » News » ISRO station picks up INSAT-3A signals

ISRO station picks up INSAT-3A signals

April 10, 2003 16:10 IST

The Indian Space Research Organisation's master control facility at Hassan, Karnataka, acquired the first telemetry signals from the multi-purpose INSAT-3A satellite at 0452 IST after the Ariane-5 rocket launched it into space.

The rocket, owned by the Arianespace Agency, took off from Kourou in French Guyana, South America, in the wee hours of Thursday.

Initial checks on the 2.9 ton satellite indicated that its performance is normal, an ISRO official said.

At its present height, the satellite is taking 10 hours 47 minutes to orbit the earth.

"First operations on the satellite were carried out by issuing commands from the MCF," the official said. "The outermost panel of the stowed solar array of the satellite 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," the official said. "During the initial phase of operations, the MCF will also utilise INMARSAT organisation's ground stations at Beijing (China), Fucino (Italy) and Lake Cowichan (Canada). The satellite's orbit is being determined by continuous ranging from the participating telemetry, tracking and command ground stations."

In the coming days, the satellite's orbit-raising operations will be carried out by firing its 440Newton liquid apogee motor in stages till the spacecraft attains its final geostationary orbit, which is about 36,000km above the equator.

The satellite has about 1.6 ton of propellant (mono-methyl hydrazine fuel and mixed oxides of nitrogen oxidiser) for the orbit-raising operations as well as for station-keeping, besides in-orbit attitude control.

The on-orbit propellant availability will enable maintaining of the satellite for operational services for 12 years.

When the satellite reaches near-geostationary orbit, deployment of its solar panels and two antennae as well as solar sail will be carried out.

The satellite will then be put in its final three-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 commissioning the satellite.

INSAT-3A will be positioned at a longitude of 93.5 deg east in the geostationary orbit. Other INSAT satellite locations are: 2DT at 55 deg east; 2E and 3B at 83 deg east; 3C and Kalpana-1 (METSAT) at 74 deg east.

When the solar panels and solar sail are fully deployed in orbit, the satellite will measure 24.4m in length. Its sun-tracking solar panels generate 3.1kW of power. Two 70Ah nickel-hydrogen batteries support full payload operations even during eclipses.

Like all its predecessors in the INSAT series, 3A is a three-axis body-stabilised spacecraft using earth sensors, sun sensors, inertial reference unit, momentum/reaction wheels, and magnetic torquers.

It is also equipped with bi-propellant thrusters. The satellite has two deployable antennae and one fixed antenna that carry out various transmission and reception functions.

Earlier, the 160th flight of Ariane, carrying INSAT-3A and Galaxi-XII of PanamSat (USA), lifted off at 0422 IST. The Indian satellite was first injected into a geo-synchronous transfer orbit, 30 minutes after lift-off, in three-axis stabilized mode, with a perigee (nearest point to earth) of 859km and apogee (farthest point from earth) of 36,055km.

INSAT-3A is the third satellite in the INSAT-3 series. INSAT-3B and INSAT-3C were launched by the Ariane-5 and Ariane-4 launch vehicles on March 22, 2000, and January 24, 2002, respectively.

The satellite is expected to augment the present INSAT capacity for communication and broadcasting, besides providing meteorological services along with INSAT-2E and Kalpana-1.

Fakir Chand in Bangalore