Chennai, Jun 22 (IANS): The 28-hour countdown for the Friday launch of India's earth observation satellite Cartosat and 30 co-passenger satellites with Polar Satellite Launch Vehicle (PSLV) began on Thursday, ISRO said.

According to the Indian Space Research Organisation (ISRO), the countdown for the launch of the satellites, that also includes 29 foreign and one Indian, from Sriharikota in Andhra Pradesh began at 5.29 a.m.

The Indian space agency said propellant filling operations were under progress.

The Mission Readiness Review (MRR) committee and Launch Authorisation Board (LAB) on Wednesday cleared the 28-hour countdown.

India on Friday will launch the Cartosat-2 series weighing 712 kg and 30 co-passenger satellites.

According to the ISRO, the PSLV rocket's XL variant was expected to lift off on Friday at 9.29 a.m. from the Sriharikota rocket port.

The 30 satellites would together weigh 243 kg and the total weight of all the 31 satellites, including Cartosat, is about 955 kg, ISRO said.

The rocket would sling the satellites into a 505 km polar sun sunchronous orbit (SSO).

The co-passenger satellites comprise 29 nano satellites from 14 countries - Austria, Belgium, Britain, Chile, Czech Republic, Finland, France, Germany, Italy, Japan, Latvia, Lithuania, Slovakia, and the US as well as one Indian nano satellite.

The 29 international customer nano satellites were being launched as part of the commercial arrangements between ISRO's commercial arm, the Antrix Corporation Ltd and the international customers.

The Indian nano satellite 15 kg NIUSAT belongs to Nooral Islam University, Tamil Nadu. The satellite will provide multi-spectral imagery for agricultural crop monitoring and disaster management support applications.