PSLV versus GSLV

PSLV

• PSLV is designed mainly to deliver the ―earth-observation or ―remote-sensing‖ satellites with lift-off mass of up to about 1750 Kg to Sun-Synchronous circular polar orbits of 600-900 Km altitude.
• PSLV is also used to launch the satellites of lower lift-off mass of up to about 1400 Kg to the elliptical Geosynchronous Transfer Orbit (GTO).
• PSLV is a four-staged launch vehicle with first and third stage using solid rocket motors and second and fourth stages using liquid rocket engines. It also uses strap-on motors to augment the thrust provided by the first stage.

GSLV

• The GSLV is designed mainly to deliver the communication-satellites to the highly elliptical (typically 250 x 36000 Km) Geosynchronous Transfer Orbit (GTO).
• The satellite in GTO is further raised to its final destination, viz., Geo-synchronous Earth orbit (GEO) of about 36000 Km altitude (and zero deg inclination on equatorial plane) by firing its in-built on-board engines.

Due to their geo-synchronous nature, the satellites in these orbits appear to remain permanently fixed in the same position in the sky, as viewed from a particular location on Earth, thus avoiding the need of a tracking ground antenna and hence are useful for the communication application.