The nearly 51-hour countdown for the launch of the Polar Satellite Launch Vehicle (PSLV-C15) from the spaceport at Sriharikota began at 6.52 a.m. on Saturday, and is progressing smoothly, officials of the Indian Space Research Organisation (ISRO) have said.

The four-stage rocket has been fully assembled and the satellites have been mated with it. The launch has been scheduled for 9.22 a.m. on Monday.

The vehicle will put in orbit five satellites: the 694-kg Cartosat-2B of the ISRO; the 116-kg Alsat-2A of Algeria; two nano satellites (the 6.5-kg NLS-6.1 built by the Space Flight Laboratory of University of Toronto, Canada, and the one-kg NLS-6.2 built by the University of Applied Sciences of Switzerland); and a very small pico satellite named Studsat, integrated by students of seven engineering colleges in Karnataka and Andhra Pradesh.

Cartosat-2B is a remote-sensing satellite whose images will be helpful in planning large-scale maps of settlements in villages and towns for development activities, in aligning new canals, laying ring roads, planning new roads in rural areas, mounting a watch on mining activities and keeping a tab on corals in the sea, mangroves or deforestation. Its images will also help in planning and developing rural and urban infrastructure and monitoring development works at the village and cadastral level. Furthermore, the images can be used for surveillance. The satellite carries a camera that can image a swath (a strip of land) of 9.6 km, with a resolution of 0.8 metres. The ISRO Satellite Centre, Bangalore, has built it.

While Alsat-2A of Nigeria is also a remote-sensing satellite, the two nano satellites have been built for testing various satellite technologies. The Studsat provided the students with a hands-on experience in building a satellite.

It is a core-alone version of the PSLV that will put these satellites in orbit one after another. While a standard PSLV version has six strap-on booster motors strung around the first stage, the core-alone version does not have these motors. The core-alone PSLV weighs 230 tonnes at liftoff and is 44 metres long.

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