Mission Readiness Review (MRR) committee and Launch Authorisation Board (LAB) had cleared the 29 hr countdown of PSLV-C39/IRNSS-1H Satellite mission which began at 1400 hrs IST on Wednesday, sources in Indian Space Research Organisation (ISRO), said. The 1425 kg spacecraft is similar to seven other IRNSS series of satellites which have already been launched. The launch will take place from the Second Launch Pad (SLP) of SDSC, ISRO’s space port, a cresent shaped island overlooking Bay of Bengal.

As in the previous six launches of IRNSS satellites, PSLV-C39 will use ‘XL’ version of PSLV equipped with six strap-ons, each carrying 12 tons of propellant. The Polar Satellite Launch Vehicle-C39, is the 41st flight of
ISRO’S workhorse PSLV. The ‘XL’ version of PSLV equipped with six strap-ons, each carrying 12 tons of propellant. With this launch, ISRO will be heralding the start of private sector Assembly and Testing of satellites.

The space agency plans to shift to total integration of satellite assembly and testing from procuring components, sub systems and systems from the private sector by 2018. Besides IRNSS satellites, PSLV-XL has also launched many other spacecraft including India’s Mars Orbiter spacecraft, the multi-wavelength observatory ASTROSAT, Radar Imaging satellite RISAT-1 and Communicate satellite GSAT-12.

The launch of 104 satellites during a single mission by PSLV in February this year was the most prominent of its recent successes. Like its other IRNSS predecessors, IRNSS-1H also carries two types of payloads navigation and ranging payload. The navigation payload will transmit navigation service signals to the users. Highly accurage Rubidium atomic clocks are part of the navigation payload of the satellite.

The ranging payload of this satellite consists of a C-band transponder which facilitates accurage determination of the range of satellite. IRNSS-1H also carries Corner Cube Retro Reflectors for laser ranging. Once launched, the satellite will be placed in sub GTO with a 284 km perigee (nearest point to Earth) and 20,650 apogee (farthest point to Earth) with an inclination of 19.2 degree with respect to equatorial plane. IRNSS-1H completes the constellation for providing navitation services which has been named NavIC (Navigation with Indian Constellation).