Chennai, Dec 13 (IANS) India will Dec 20 launch the advanced GSAT-5P communication satellite that will replace the ageing INSAT 2E and ensure continuity of telecom and television services, an official said.

"The launch window will open at 1600 hours on Dec 20," Indian Space Research Organisation (ISRO) director (publications and public relations) S. Satish told IANS.

Carrying the 2,300 kg GSAT-5P with 36 transponders, India's heavy rocket - the geosynchronous satellite launch vehicle (GSLV) - will blast off from ISRO's second launch pad at Sriharikota, around 80 km from here between 4 and 4.30 p.m.

According to officials, the fully assembled rocket was moved to the launch pad and anchored there Sunday morning around 7.45 a.m. The satellite was placed inside the heat shield last week.

ISRO officials told IANS that the process of filling the liquid and cryogenic fuel will begin around 30 hours before the actual flight when the countdown begins.

Prior to the countdown, ISRO will test the rocket's various systems. Its full systems test will be done Monday (Dec 13).

According to ISRO officials, the launch rehearsal will be held on Dec 17 but without the liquid and cryogenic fuel.

"If satisfied with the rocket's condition then the final clearance for the flight will be given. Then the rocket will be `armed'- connecting of all pyro systems to the batteries - so that they ignite when the command is given," said an ISRO official.

ISRO is also likely to begin the New Year with the launch of Resourcesat-2, an earth observation satellite.

Remote sensing satellites send back pictures and other data for use. India is a major player in vending such data in the global market.

"Resourcesat-2 will be the replacement for Resourcesat-1, launched in 2003. For some time, both will work together," Satish added.

Piggy-backing on it will be two small satellites made in Singapore and Russia.

The satellites will be carried by ISRO's another rocket called polar satellite launch vehicle (PSLV) and the launch date is around Jan 20.

According to ISRO officials the Resourcesat-2 and another small satellite are expected to reach Sriharikota by December end.

ISRO this year launched two major satellites - communication satellite GSAT-4 and remote sensing satellite Cartosat-2. While the launch of GSAT-4 failed as the GSLV rocket carrying it plunged into the sea due to an engine failure, Cartosat-2 was placed successfully in the orbit.