IRNSS-1A was the first satellite of India's regional navigation system, NavIC. PSLV-C22 launched it from Sriharikota in July 2013.
IRNSS-1A opened the space segment of the Indian Regional Navigation Satellite System (IRNSS), later named NavIC. The system is planned around seven satellites and is meant to give accurate positions across India and up to about 1,500 km beyond its borders.
IRNSS-1A carries two payloads. The navigation payload broadcasts NavIC signals in the L5 and S bands, timed by a rubidium atomic clock. The ranging payload is a C-band transponder that lets ground stations measure the satellite's distance precisely. Corner-cube retro-reflectors on the body allow laser ranging from the ground.
The satellite weighed 1,425 kg at lift-off and is a box about 1.58 m × 1.50 m × 1.50 m. Two solar panels supply about 1,660 W. A 440 N liquid apogee motor and twelve 22 N thrusters move the satellite, while reaction wheels, magnetic torquers and thrusters keep it pointed, using Sun sensors, star sensors and gyroscopes. A 90 ampere-hour lithium-ion battery stores power.
PSLV-C22 lifted off from the First Launch Pad at Sriharikota in July 2013. It was the fourth flight of the more powerful PSLV-XL version. IRNSS-1A was designed to work from an inclined geosynchronous orbit crossing the equator at 55° East, tilted 29° to the equator.
IRNSS-1A suffered failures in its atomic clocks, so ISRO built spare satellites to replace it. The first replacement, IRNSS-1H, reached orbit in 2017 but was lost because its heat shield did not separate. ISRO says IRNSS-1A still provides a messaging service to users in the Indian region. The public satellite catalogue lists IRNSS-1A as degraded.