The 71-hour countdown for the launch of 1,858 kg RISAT -1, India's radar imaging satellite, the heaviest one to be lifted by ISRO's Polar Satellite Launch Vehicle commenced on Monday morning.
"The countdown for radar sensing satellite RISAT-1 started this morning at 6.47 AM at Sriharikota. This is a 71- hour long countdown," an ISRO spokesman said.
The launch is scheduled at 5.47 AM on April 26 from the Satish Dhawan Space Centre at Sriharikota in Andhra Pradesh.
India currently depends on images from a Canadian satellite as domestic remote sensing spacecraft cannot take pictures of the ground during cloud cover.
"This (Radar Imaging Satellite or RISAT-1) is about 1,850 kg. So this will be heaviest satellite lifted by a PSLV (Polar Satellite Launch Vehicle)," ISRO Chairman K. Radhakrishnan had earlier said.
The approved cost of RISAT-1, including its development, is Rs 378 crore, while Rs 120 crore has been spent to build the rocket (PSLV-C19), making it a Rs 498-crore mission.
RISAT-1 will be launched into a 536-km orbit by PSLV, India's workhorse rocket.
The satellite carries a C-band Synthetic Aperture Radar (SAR) payload, operating in a multi-polarisation and multi-resolution mode to provide images with coarse, fine and high spatial resolutions.