Understand the difference between PSLV and GSLV.

You might have heard about PSLV and GSLV rocket launch systems developed by the Indian Space Research Organization, or ISRO, to launch satellites into orbit.In this article we will understand the difference between PSLV and GSLV.

This is the basic difference between GSLV (Geosynchronous Satellite Launch Vehicle) and PSLV (Polar Satellite Launch Vehicle).

Both PSLV (Polar Satellite Launch Vehicle) and GSLV (Geosynchronous Satellite Launch Vehicle) are the satellite-launch vehicles (rockets) developed by ISRO. The PSLV is the older of the two and the GSLV even inherits some of the technologies of the former in its design.

The main reason behind the advent of the GSLV is the capability to lift greater loads into space. While the PSLV can only lift slightly over a ton of payload to GTO (Geostationary Transfer Orbit), the GSLV is capable of lifting more than double that with a rated capacity of 2 to 2.5 tons. One of the main reasons why the GSLV has such an increased load is its utilization of a cryogenic rocket engine for its last stage. The cryogenic rocket engine provides more thrust than conventional liquid rocket engines but the fuel and oxidizer needs to be super cooled in order to keep them in a liquid state.

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, and depending on the number of these strap-on boosters, the PSLV is classified into its various versions like core-alone version (PSLV-CA), PSLV-G or PSLV-XL variants.

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.

When you look at their track records, it is easy to see that the PSLV is more reliable. With 18 launches, 16 of those were successes while only the first one was a total failure; the remaining one is called a partial failure as the satellite did not reach the intended altitude. The 7 launches of the GSLV have had worse results with 4 ending in failure and only two successes; it also has one partial failure launch.

In short:

1.The PSLV is older than the GSLV
2.The GSLV has a much greater load capacity than the PSLV
3.The GSLV use cryogenic fuel while the PSLV doesn’t
4.The GSLV has three stages while the PSLV has four stages
5.The GSLV has 4 liquid boosters while the PSLV has 6 solid boosters
6.The PSLV is more reliable than the GSLV