Isro to launch fourth navigational satellite on 9 March

Indian Space Research Organization (Isro) is all set to launch IRNSS-1D, the fourth satellite in the Indian Regional Navigational Satellite System (IRNSS), on 9 March.

IRNSS-1D is the fourth out of seven in the Indian Regional Navigational Satellite System (IRNSS) series of satellites after IRNSS-1A, IRNSS-1B and IRNSS-1C. The IRNSS constellation of satellites, which will be placed in geosynchronous orbit, will provide navigational services to the region.

The satellite will be launched on board the Polar Satellite Launch Vehicle (PSLV-C27), the workhorse rocket of the Indian space agency, at 6.35 pm from the Salish Dawn Space Centre at Sriharikota.

IRNSS, which is currently under development, is designed to provide accurate position information service to users in India as well as the region extending up to 1,500 km from its boundary, a position accuracy of better than 20 metres in its primary service area.

The first satellites are placed in suitable orbital slots in the geostationary orbit, a circular orbit 35,786km above the equator and the IRNSS-1D and the three remaining satellites will be placed in geosynchronous orbits, which are elliptical orbits designed to keep communication satellites within the view of ground stations.

The constellation will help augment the satellite based navigation system in India and its neighbouring countries. It will also reduce India's dependence on foreign systems such as the US global positioning system and the Russian global navigation satellite system.

The system will provide two types of services, including Standard Positioning Service (SPS), which is provided to all the users and Restricted Service (RS), which is an encrypted service provided only to the authorised users.

''With the launch of the fourth satellite, we will be able to start getting accurate positioning information on the ground and they will start evaluating the proof of concept of the navigation project involving the ground support system,'' an Isro spokesman said.

The fifth IRNSS satellite is expected to be launched by September.

The IRNSS launch will be followed by a commercial satellite launch aboard the PSLV and the GSAT-6 satellite launch aboard the GSLV-D6 with an indigenous cryogenic engine.

Isro is also planning to launch India's first dedicated astronomical satellite, ASTROSAT, before the end of the year.