India's communication satellite GSAT-12, put in orbit on July 15, reached its home in a circular geo-synchronous orbit at an altitude of 36,000 km on Tuesday. The Polar Satellite Launch Vehicle (PSLV-C17) of the Indian Space Research Organisation (ISRO), which lifted off from the space station at Sriharikota on July 15, 2011, put the 1,410 kg GSAT-12 in a sub geo-synchronous transfer orbit (sub-GTO) with an apogee of 21,020 km and a perigee of 284 km.

Challenging operation

After the satellite was put in a sub-GTO, the liquid apogee motor (LAM) on board was fired once each day from July 16-19 to circularise the orbit at an altitude of 36,000 km. On July 16 and 17, commands were given from the Master Control Facility (MCF) at Hassan in Karnataka to the LAM to take the satellite's apogee from 21,020 km to 36,000 km when the satellite was at its perigee. Similarly, the commands to the LAM to fire to take the perigee from 284 km to 36,000 km were given on July 18 and 19 when the satellite was at its apogee. “Thus, it was a challenging operation,” said an ISRO official.

“But all operations went off well. The sub-systems on board the satellite are functioning normally. The satellite has now made it to its final, circular geo-synchronous orbit of 36,000 km,” he added.

The LAM will be fired again on Wednesday for final trimming of the satellite's orbit.

With 12 extended C-band transponders, the satellite will be useful in tele-education, tele-medicine, disaster management support, telephone services and so on.

Two more this year

This year ISRO will launch two more satellites.

It is now getting ready for the launch of Megha-Tropiques satellite, an Indo-French joint venture, from the spaceport at Sriharikota by the end of September.

The PSLV-C18 will put the 1,000-kg Megha-Tropiques (Megha in Sanskrit means cloud and Tropiques in French means tropics), being built by the ISRO Satellite Centre, Bangalore, into an 867 km orbit. It will be useful in studying the weather in tropical countries.

For surveillance

ISRO is also building for surveillance, RISAT-1 (Radar Imaging Satellite) which will be put in orbit by the end of December by PSLV-C19.

It can take pictures of the earth day and night and in all weather conditions.

More In: National | News | Sci-Tech | Science