GSLV - Geosynchronous Satellite Launch Vehicle

ISRO developed the PSLV into an Ariane-Class Geosynchronous SLV with a 3.6 meter diameter fairing, capable of handling 2.5 ton INSAT-3 satellites. Some 500 configurations were reduced to four candidates during 1986-1988, divided equally between solid and liquid cores and both with solid and liquid strap-ons. The GSLV will replace the PSLV's six solid strap-ons with liquids and substitute a cryogenic stage for the two upper stages. The cryogenic engine is being developed by Russia under a Rs.2350 million agreement signed with Glavcosmos in January 1991. First delivery was expected to be 1994-1995 but due to the ban imposed by the United States on Russia to export any missile-related equipment to India - the delivery was delayed. However, during the later half of 1996, Russia assured that the engines will be delivered. India is also in the mean time reported to be developing the engines indigenously. The GSLV had its first flight on 18 April 2001.

Visit ISRO's website on the GSLV-D1

GSLV Facts at a Glance

Launch Mass: 401 tons.

Length: 50.9 meters.

Strap-ons: Has four L-40 engines, each having 40 tons of UDMH (Unsymmetrical DiMethyl Hydrazine) and NTO (Nitrogen TetrOxide). PSLVs Vikas engine is due to replace the L-40 engines as the GSLVs strap-ons.

Stage 1: S-125, as the PSLV Stage 1 (129 tons solid).

Stage 2: (GS2) is powered by a single liquid propellant engine (L37.5) - same as the PSLV.

Stage 3: (GS3) is a cryogenic stage (C12) with re-startable engines. Length - 8.7m, Diameter - 2.8m, Mass - 15t (of which 12.5t is for the propellant). Propellant - LH2 (Liquid Hydrogen) & LOX (Liquid Oxygen)