BENGALURU: The fourth and the final orbit raising operation of April 12-launched IRNSS-1I satellite was successfully carried out at 9.05 pm on Sunday. With the completion of the series of four orbit-raising operations, the satellite is now close to its space home at 55 degree East longitude in the planned geosynchronous orbit, with an inclination of 29 degree to the equator, at an altitude of about 36,000 Km. A geosynchronous orbit is when the satellite is in an almost stationary position with relation to a point on earth.
The IRNSS-1I is the eighth satellite in the constellation, with seven others already in space, which are part of the navigation with Indian Constellation (NavIC) system — originally called Indian Regional Navigation Satellite System, or IRNSS. This system will provide Indian land-based users indigenous positioning and navigation services.
The third orbit-raising operation of IRNSS-1I was carried out on Saturday night to achieve a perigee (closest distance to earth) height of 31,426 Km and apogee (farthest distance from earth) height of 35,739 Km, while the second orbit-raising manoeuvre of IRNSS-1I was carried out on Friday night. The Indian Space Research Organisation’s (ISRO) master control facility (MCF) at Hassan performed the first orbitraising operation on Friday morning.
The 1,425 Kg IRNSS-1I was launched at 4.04 am on April 12 on board PSLV-C41 from ISRO’s first launch pad at Satish Dhawan Space Centre, Sriharikota. It was the 43rd flight of ISRO’s workhorse launcher Polar Satellite Launch Vehicle. The IRNSS- 1I now joins seven other satellites of the IRNSS constellation — IRNSS-1A, 1B, 1C, 1D, 1E, 1F and 1G — which is already in place over India.
According to a top ISRO official, the completion of IRNSS-1I’s orbit- raising manoeuvres has come as a relief to the space scientists of the country’s premier space agency, especially after it lost the communication link with its most sophisticated communication satellite, GSAT-6A, on March 31 morning after the satellite was launched on March 29. The scientists at MCF Hassan, in Karnataka, lost communication link just after completing the second orbitraising manoeuvre and were preparing for the third and final orbit- raising operations on April 1.
The ISRO scientists have so far been unable to re-establish communication links with GSAT-6A, which is still orbiting the earth. The mission life of GSAT-6A was planned for about 10 years. The satellite was planned to provide a platform for developing technologies such as demonstration of 6-metre S-Band unfurlable antenna, hand-held ground terminals and network management techniques that could be useful in satellite-based mobile communication applications — mainly for the armed forces in remote areas.