Polar Satellite Launch Vehicle, in its 33rd flight (PSLV-C31), launches IRNSS-1E, the fifth satellite of the Indian Regional Navigation Satellite System (IRNSS). The launch took place from the Second Launch Pad (SLP) of Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota on January 20, 2016 at 09:31 Hrs (IST). As in the previous four launches of IRNSS satellites, PSLV-C31 used ‘XL’ version of PSLV. This is the eleventh time ‘XL’ configuration is being flown, earlier ten being PSLV-C11/Chandrayaan-1, PSLV-C17/GSAT-12, PSLV-C19/RISAT-1, PSLV-C22/IRNSS-1A, PSLV-C25/Mars Orbiter Spacecraft, PSLV-C24/IRNSS-1B, PSLV-C26/IRNSS-1C, PSLV-C27/IRNSS-1D, PSLV-C28/DMC-3 and PSLV-C30/ASTROSAT missions.
IRNSS-1E with a lift-off mass of 1425 kg, is the fifth navigation satellite of the seven satellites constituting the IRNSS space segment. Its predecessors, IRNSS-1A, 1B, 1C and 1D were launched by PSLV-C22, PSLV-C24, PSLV-C26 and PSLV-C27 in July 2013, April 2014, October 2014 and March 2015 respectively. The configuration of IRNSS-1E is similar to that of IRNSS-1A, 1B, 1C and 1D. IRNSS -1E carries two types of payloads – navigation payload and ranging payload. The navigation payload of IRNSS-1E transmits navigation service signals to the users. This payload is operating in L5-band and S-band. A highly accurate Rubidium atomic clock is part of the navigation payload of the satellite. The ranging payload of IRNSS-1E consists of a C-band transponder which facilitates accurate determination of the range of the satellite. IRNSS-1E also carries Corner Cube Retro Reflectors for laser ranging.