Chennai: Metsat, Indias first meteorological satellite, placed on the Geosynchronous Transfer Orbit (GTO) on 12 September 2002, was successfully manoeuvred from the Mission Control Facility (MCF) at Hassan, Karnataka.

The manoeuvre was done by firing the satellites liquid apogee motor for 31.49 minutes on the morning of 13 September. The satellite carries 560kg of fuel. With this, Metsat is now orbiting Earth with a perigee (nearest point to Earth) of 12,100 km and an apogee (farthest point to Earth) of 34,500 km.

The inclination of the orbit has been reduced from 17.67 degree at the time of injection to 5 degree. According to Indian Space Research Organisation (ISRO), the intended intermediate orbit has been precisely realised. A few more orbital manoeuvres will be required before the satellite is finally placed in geostationary orbit and moved to its designated slot at 74 degree East longitude in that orbit.

The operations are likely to be completed in the next few days. Flight to glory 1211 seconds or 20 minutes after the blast off at 3.53 pm, the 295 t, 44.4 m tall Polar Satellite Launch Vehicle (PSLV-C4) slung its payload the 1055 kg Metsat over Indonesia at a GTO of 218 km perigee (nearest point to Earth) and 34,700 km apogee (farthest point to Earth).

The elliptical orbit will be inclined at angle of 17.7 degrees to the equator. There were anxious moments 15 minutes before the blast off due to some minor snag in the computer systems. As a result the blast-off time was put back by just one minute.

Speaking about the successful launch, ISRO chairman K Kasturirangan: For the first time we have launched an exclusive satellite. Future meteorological satellites can go with complex and a higher resolution camera. We will have more transponders in Insat and extend its life to 15 years.

Metsat is the first exclusive meteorological satellite built by ISRO and a precursor to the future INSAT system that will have separate satellites for meteorology and telecommunication and broadcasting services. This will enable building of transponders and their radiated power, into Insat satellites, without the design constraints imposed by meteorological instruments.

The satellite carries a very high-resolution radiometer (VHRR), capable of imaging Earth in the visible, thermal infra-red and water vapour bands. It also carries a data relay transponder (DRT) for collecting data from unattended meteorological platforms. Immediately after injection into GTO, Metsats 550 watts solar array was automatically deployed.

The onboard 18 Ampere-Hour Nickel-Cadmium battery will supply electrical energy when the satellite is in the earth's shadow (eclipse). One of the new elements used in Metsat is the light-weight planar array antenna which transmits the data from the VHRR and DRT. Similarly, ISRO has used spacecraft bus employing lightweight structural elements like carbon fibre reinforced plastic.

The deployment of the array as well as the general health of the satellite will be monitored by a ground station of the ISRO telemetry, tracking and command network (ISTRAC) located on the Indonesian island of Biak. While the MCF, Hassan takes control of Metsat for all its post launch operations ground stations at Lake Cowichan (Canada), Fucino (Italy) and Beijing (China) will support MCF in monitoring the health of the satellite and its orbit raising operations.