BANGALORE, India — The Indian Space Research Organisation (ISRO) successfully launched the fourth satellite for its space-based regional navigation system March 28 in a mission that gives the constellation enough satellites to provide initial service.

The launch, originally scheduled for March 9 but delayed due to technical concerns, placed the 1,425-kilogram Indian Regional Navigation Satellite System (IRNSS)-1D into an elliptcal transfer orbit with a perigee of 282.5 kilometers and an apogee of 20,644 kilometers. The satellite will be manuvered into a geosynchronous orbit with a 30.5 degree inclination at 111.75 degrees east longitude, ISRO said.

The nationally televised launch was carried out from the Satish Dhawan Space Center in Sriharikota on the country’s southeastern coast by ISRO’s workhorse Polar Satellite Launch Vehicle, which was making its 27th flight.

IRNSS-1D shown between the heat shield of its PSLV launch vehicle
IRNSS-1D shown between the heat shield of its PSLV launch vehicle. Credit: ISRO

In a post-launch update, ISRO said the initial orbit-raising maneuver was successfully completed March 30, raising the satellite’s perigee to 314 kilometers and apogee to 35,653 kilometers.

When fully deployed by sometime in 2016, the 14.2 billion rupee ($226 million) IRNSS will consist of seven nearly identical satellites, three in geostationary orbit, two in inclined geosynchronous orbits and two spares. The first three satellites, launched last year, are in position and functioning well, according to ISRO.

IRNSS project director P. Kunhikrishnan said that once IRNSS-1D is in place, the four initial satellites would meet the minimum requirement to start operations of the IRNSS system.

“This would provide in-orbit availability of a 4-satellite constellation to start the testing phase of user equipment,” ISRO Chairman A.S. Kiran Kumar told SpaceNews in an earlier interview. “We plan to realize the complete system by 2016,” he said.

The next satellite, IRNSS-1E, will be ready for launch this coming June, according to S.K. Shivkumar, director of the ISRO Satellite Centre here.

Like its companions, IRNSS-1D satellite has two payloads for navigation and ranging, and the design makes the IRNSS system interoperable with the U.S. GPS and European Galileo systems, ISRO said. The IRNSS satellites are designed to operate for 10 years.

ISRO said the IRNSS is designed to provide positioning information accurate to within 20 meters to users in a region that includes all of India and extends to 1,500 kilometers beyond the nation’s borders. IRNSS ground control and signal monitoring and ranging stations have been established in 15 locations across India.


Based in Bangalore, Killugudi S. Jayaraman holds a doctorate in nuclear physics from the University of Maryland and a master's degree in journalism from the Medill School of Journalism at Northwestern University. He was formerly science editor of the...